Timothy Chandler played like he "was never away" in Eintracht Frankfurt's 2-1 win at Hamburg after returning to action from injury, sporting director Fredi Bobic has said.
United States international Chandler played the full 90 minutes and set up the winner on his comeback from a lateral meniscus tear suffered in October.
Kovac opted not to substitute Chandler, although teammate Marco Russ said the defender was "looking like he was about to faint right after half-time."
"Given our unbelievable team performance, I just had to fight until the very end," Chandler told reporters, adding that it had been difficult for him "to bite through after such a long absence."
The American, playing at right wing-back, had his hand in both Frankfurt goals and added pace to the attack down that side.
"It was no surprise Timothy made it through the entire 90 minutes," Kovac said, while sporting director Fred Bobic added: "He played like he never was away."
Frankfurt have taken 25 points from their first 16 matches of the season, and are the Bundesliga's best away side with 18 points from nine matches. They host second-placed Schalke on Saturday.